1. Field of the Invention
This invention relates generally to the field of electronic device user interfaces and authorization techniques, and more specifically to the field of fingerprint imaging sensors and touch screen display apparatuses.
2. Necessity of the Invention
Modern electronic devices have developed a myriad of functionalities and associated user interfaces. Many electronic devices use a display screen, such as a monitor or display apparatus, to provide feedback to the user. Handheld devices, such as the personal digital assistant and the cell phone, have an important user interface constraint—form factor. In both devices, manufacturers desire to minimize the size and weight of the device; as one means to accomplish this, the display is small and buttons are placed close together.
In recent years, manufacturers of many electronic devices have substituted touch screen technology for the traditional display. Touch screens have the same appearance and style of a traditional screen, but have the added ability to determine the location of applied pressure. This allows individuals to use a stylus in a similar manner as a person uses a mouse to point to icons on a monitor—the individual may touch the screen at the location of a particular icon. Software running on the device determines the location of the touch and determines the associated software function, such as opening an address book. Because the additional button control interface can be eliminated, manufacturers can make the display larger and simpler to use.
As the functionality of electronic devices expands, individuals may wish to protect certain data stored within the device. For example, the owner of a personal digital assistant may choose to use his PDA to send and receive private e-mail. If the data is particularly sensitive, a simple password or PIN combination may not be considered adequate security and the individual may desire to use biometric authentication on the device. The most common form of biometric authentication, fingerprint scanning, requires a hardware module that is typically the size of a postage stamp. On a device where size and weight are limited, the addition of this module can be costly.